Human intestinal epithelial cells express functional cytokine receptors sharing the common γc chain of the interleukin 2 receptor

Interleukin (IL) 2 signaling requires the dimerization of the IL-2 receptor β (IL-2Rβ) and common γ (γc) chains. The γc is also a component of the receptors for IL-4, IL-7, and IL-9. To assess the extent and role of the receptor signal transducing system utilizing the γc chain on human intestinal epithelial cells, the expression of γc, IL-2Rβ, and receptor chains specific for IL-4, IL-7, and IL-9 was assessed by reverse transcription-coupled PCR on human intestinal epithelial cell lines and on isolated primary human intestinal epithelial cells. Caco-2, HT-29, and T-84 cells were found to express transcripts for the γc and IL-4R chains constitutively. IL-2Rβ chain expression was demonstrated in Caco-2 and HT- 29 but not in T-84 cells. None of the cell lines expressed mRNA far the IL- 2Rα chain. After stimulation with epidermal growth factor for 24 h Caco-2, HT-29, and T-84 cells expressed transcripts for IL-7R. In addition, Caco-2 and HT-29 cells expressed mRNA for the IL-9R. Receptors for IL-2, IL-4, IL- 7, and IL-9 on intestinal epithelial cells lines appeared to be functional; stimulation with these cytokines caused rapid tyrosine phosphorylation of proteins. The relevance of the observations in intestinal epithelial cell lines for intestinal epithelial function in viva was supported by the demonstration of transcripts for γc, IL-2Rβ, IL-4R, IL-7R, and IL-9R in primary human intestinal epithelial cells.